Skin the fish and cook in a large saucepan in boiling oil for 15 minutes. Remove from the oil and drain. Cut the onions, cabbage, pork, mushrooms and lily petals into slices 1½ inches long, put all in a hot oiled pan and cook for 5 minutes. Then add the fish, cover with stock and cook for 5 minutes. Add a little cornflour water, a few drops of Chinese sauce, and sugar and salt to taste.